336 



TEMPERATURE COEFFICIENT OF PHAGOCYTOSIS 



length of the latent period by the formula of Arrhenius, and found 

 n = 15,000 and 16,350 respectively in their paper. ^ The data fit the 

 simpler formula of van't Hoff equally well and gives ^lo as 2.35 and 

 2.6, respectively. 



A second complicating reaction is evidenced in Fig. 1 by the fact 

 that at higher temperatures phagocytosis ceases; i.e., the maximum is 

 reached sooner than at lower temperatures. This indicates that 

 some secondary reaction is occurring which results in injury to the 

 cells or otherwise makes phagocytosis impossible.^ The speed of this 

 "lethal reaction," as we may call it, increases with the temperature. 

 If the phagocytic reaction itself were accelerated by rise of temperature 



to the same degree as the lethal reaction, the maximum reached would 

 be the same at all temperatures, for the more rapid phagocytosis 

 at higher temperatures would just compensate for the shorter time 

 available. Therefore, the fact that the maximum attained is higher 

 at the higher temperatures, in spite of the shorter time, proves that 

 the temperature coefficient of phagocytosis must be higher than the 

 temperature coefficient of the lethal reaction. 



In Fig. 4 are plotted graphs from which the Qiq of the lethal reaction 

 can be approximated. Ordinates represent logarithms of the recip- 

 rocals of the time necessary for completion of the reaction, i.e., time to 

 reach the maximum; abscissae represent temperature. These figures 

 are, of course, highly inaccurate, probably particularly so at tem- 



^ The maximum cannot be due entirely to any mechanical factor such as the 

 exhaustion of the available bacteria or the filling up of the cells or it would be 

 the same in all. The lethal reaction which determines the maximum might be 

 referred to the toxic action of bacterial extracts. 



